One scheme for protecting a structural member such as a substrate disposed adjacent a relatively high temperature environment such as the hot exhaust gas stream of a gas turbine engine flowing within an exhaust nozzle or conduit, is to provide a relatively thin sheet of material disposed between the hot environment and the substrate for forming a thermal shield therebetween.
Such sheets may further be protected by supplying a flow of cooling air between the sheet liner and the supporting substrate. The problem of securing the liner to the substrate involves providing a fastener arrangement which is able to itself resist the high temperature environment and is preferentially uncomplicated in design.
For gas turbine engine exhaust nozzles having movable flaps disposed adjacent to the high temperature exhaust gases, a protective liner disposed between, for example, the flap substrate and the hot gases must be releasable from within the gas flow path in order to provide for replacement of the liner as well as to allow access to the internal structure of the flap for servicing thereof. As such fasteners must be accessible from the hot gas side, means for protecting any exposed fastener surface or structure must be provided by any successful arrangement in order to avoid burnout or over temperature of the fastener. A protected fastener arrangement adds additional protecting structure which may be expensive and time-consuming to remove in order to release the protected fastener.
What is needed is a temperature resistant fastener arrangement which is easily releasable from the hot gas side and which does not require additional protective structure against the adjacent high temperature environment.